User:Anmclarke/sandbox

=Solar tracker bits=

Clouds
The above models assume uniform likelihood of cloud cover at different times of day or year. In different climate zones cloud cover can vary with seasons, affecting the averaged performance figures described above. Alternatively, for example in an area where cloud cover on average builds up during the day, there can be particular benefits in collecting morning sun.

Atmosphere
The distance that sunlight has to travel through the atmosphere increases as the sun approaches the horizon, as the sunlight has to travel diagonally through the atmosphere. As the path length through the atmosphere increases, the solar intensity reaching the collector decreases. This increasing path length is referred to as the air mass (AM) or air mass coefficient, where AM0 is at the top of the atmosphere, AM1 refers to the direct vertical path down to sea-level with Sun overhead, and AM greater than 1 refers to diagonal paths as the Sun approaches the horizon.

Interestingly, even though the sun may not feel particularly hot in the early mornings or during the winter months, the diagonal path through the atmosphere has a less than expected impact on the solar intensity. Even when the Sun is only 15° above the horizon the solar intensity can be around 60% of its maximum value, around 50% at 10° and 25% at only 5° above the horizon. Therefore trackers can deliver benefit by collecting the significant energy available when the Sun is close to the horizon.

Solar cell efficiency
Of course the underlying power conversion efficiency of a photovoltaic cell has a major influence on the end result, regardless of whether tracking is employed or not. Of particular relevance to the benefits of tracking are the following:

Molecular structure
Much research is aimed at developing surface materials to guide the maximum amount of energy down into the cell and minimize reflective losses.

Temperature
Photovoltaic solar cell efficiency decreases with increasing temperature, at the rate of about 0.4%/°C. For example 20% higher efficiency at 10°C in early morning or winter as compared with 60°C in the heat of the day or summer. Therefore trackers can deliver additional benefit by collecting early morning and winter energy when the cells are operating at their highest efficiency.

Summary
Trackers for concentrating collectors must employ high accuracy tracking so as to keep the collector at the focus point.

Trackers for non-concentrating flat-panel do not need high accuracy tracking:
 * low power loss: under 10% loss even at 25° misalignment
 * reflectance consistent even to around 50° misalignment
 * diffuse sunlight contributes 10% independent of orientation, and a larger proportion on cloudy days

The benefits of tracking non-concentrating flat-panel collectors flow from the following:
 * power loss degrades rapidly beyond about 30° misalignment
 * significant power is available even when the Sun is very close to the horizon, e.g. around 60% of full power at 15° above the horizon, around 50% at 10°, and even 25% at only 5° above the horizon – of particular relevance at high latitudes and/or during the winter months
 * photovoltaic panels are around 20% more efficient in the cool of the early mornings as compared with during the heat of the day; similarly more efficient in winter than summer – and to effectively capture early morning and winter sun requires tracking.

=HDMI bits=


 * In ===Cables=== fix: An HDMI cable is usually composed of four shielded twisted pairs, with impedance of the order of 100 Ω, plus several separate conductors.

=Ethernet bits=

Ethernet over twisted-pair is typically implemented using the following methods:

=VERNet (network)=

VERNet or Victorian Education and Research Network (VERN) provides optical fibre transmission services, both dark fibre and Wave-division multiplexing (WDM).

VERNet Pty Ltd, which owns and operates the VERN, was formed in 2004. The shareholders are the 9 universities in Victoria and the Australian CSIRO.

Typos and bits to update

 * Add link to VERNet page (when created)